The field relates generally to doubly-fed induction generator (DFIG)-based uninterruptible power supply systems, and more specifically, to offline DFIG-based uninterruptible power supply systems with controllable power outputs.
Robust power systems enable supplying power to one or more loads. Such power systems may include combinations of generation, transport, rectification, inversion and conversion of power to supply energy for electronic, optical, mechanical, and/or nuclear applications and loads. When implementing power systems and architectures, practical considerations include cost, size, reliability, and ease of implementation.
In at least some known power systems, one or more uninterruptible power supplies (UPSs) facilitate supplying power to a load. UPSs facilitate ensuring that power is continuously supplied to one or more critical loads, even when one or more components of a power system fail. Accordingly, UPSs provide a redundant power source. UPSs may be utilized in a number of applications (e.g., utility substations, industrial plants, marine systems, high security systems, hospitals, datacomm and telecomm centers, semiconductor manufacturing sites, nuclear power plants, etc.). Further, UPSs may be utilized in high, medium, or low power applications. For example, UPSs may be used in relatively small power systems (e.g., entertainment or consumer systems) or microsystems (e.g., a chip-based system).
At least some known UPSs include a transformer coupled between a load and a medium voltage inverter. The inverter converts power received from a direct current (DC) power source into an alternating current (AC) power signal that is transferred to the load via the transformer. Although the inverter may be controllable to provide the load with variable voltage from the DC power source, the inverter may not have the capabilities to provide the required power quality to the load in the event of a power disturbance.